linux-toradex.git/drivers/firewire/core-transaction.c, branch v3.4.73

firewire: core: convert AR-req handler lock from _irqsave to _bh

2012-02-22T21:36:01+00:00

fw_core_handle_request() is called by the low-level driver in tasklet
context or process context, and fw_core_add/remove_address_handler() is
called by mid- or high-level code in process context.  So convert
address_handler_lock accesses from those which disable local IRQs to
ones which just disable local softIRQs.

Signed-off-by: Stefan Richter

firewire: core: fix race at address_handler unregistration

2012-02-22T21:36:01+00:00

Fix the following unlikely but possible race:

CPU 1                             CPU 2
------------------------------------------------------------------------
AR-request tasklet
    lookup handler
                                  unregister handler
				  free handler->callback_data or handler
    call handler->callback

The application which registered the handler has no way to stop nodes
sending new requests to their address range, hence cannot prevent this
race.

Fix it simply by extending the address_handler_lock-protected region
from only around the lookup to around both lookup and call.  We only
need to do so in the exclusive region handler; the FCP region handler
already holds the lock around the handler->callback call.

Alas this removes the current ability to execute the callback in
parallel on different CPUs if it was called for different FireWire cards
at the same time.  (For a single card, the handler is already
serialized.)  If this loss of a rather obscure feature is not tolerable,
a more complex fix would be required:  Add a handler reference counter;
wait in fw_core_remove_address_handler() for this conter to become zero.

Signed-off-by: Stefan Richter

firewire: core: remove obsolete comment

2012-02-22T21:36:00+00:00

Target-like applications or peer-to-peer-like applications require the
global address handler registration which we have right now, or a per-
card registration.  And node lookup, while it would be nice to have,
would be impossible in the brief time between self-ID-complete event and
completion of firewire-core's topology scanning.

Signed-off-by: Stefan Richter

firewire: core: prefix log messages with card name

2012-02-22T21:36:00+00:00

Associate all log messages from firewire-core with the respective card
because some people have more than one card.  E.g.
    firewire_ohci 0000:04:00.0: added OHCI v1.10 device as card 0, 8 IR + 8 IT contexts, quirks 0x0
    firewire_ohci 0000:05:00.0: added OHCI v1.10 device as card 1, 8 IR + 8 IT contexts, quirks 0x0
    firewire_core: created device fw0: GUID 0814438400000389, S800
    firewire_core: phy config: new root=ffc1, gap_count=5
    firewire_core: created device fw1: GUID 0814438400000388, S800
    firewire_core: created device fw2: GUID 0001d202e06800d1, S800
turns into
    firewire_ohci 0000:04:00.0: added OHCI v1.10 device as card 0, 8 IR + 8 IT contexts, quirks 0x0
    firewire_ohci 0000:05:00.0: added OHCI v1.10 device as card 1, 8 IR + 8 IT contexts, quirks 0x0
    firewire_core 0000:04:00.0: created device fw0: GUID 0814438400000389, S800
    firewire_core 0000:04:00.0: phy config: new root=ffc1, gap_count=5
    firewire_core 0000:05:00.0: created device fw1: GUID 0814438400000388, S800
    firewire_core 0000:04:00.0: created device fw2: GUID 0001d202e06800d1, S800

This increases the module size slightly; to keep this in check, turn the
former printk wrapper macros into functions.  Their implementation is
largely copied from driver core's dev_printk counterparts.

Signed-off-by: Stefan Richter

firewire: use clamp and min3 macros

2011-10-09T15:00:18+00:00

Use kernel.h's convenience macros.  Also omit a printk that should never
happen and won't matter much if it ever happened.

Signed-off-by: Stefan Richter

firewire: sbp2: parallelize login, reconnect, logout

2011-05-10T20:53:46+00:00

The struct sbp2_logical_unit.work items can all be executed in parallel
but are not reentrant.  Furthermore, reconnect or re-login work must be
executed in a WQ_MEM_RECLAIM workqueue.

Hence replace the old single-threaded firewire-sbp2 workqueue by a
concurrency-managed but non-reentrant workqueue with rescuer.
firewire-core already maintains one, hence use this one.

In earlier versions of this change, I observed occasional failures of
parallel INQUIRY to an Initio INIC-2430 FireWire 800 to dual IDE bridge.
More testing indicates that parallel INQUIRY is not actually a problem,
but too quick successions of logout and login + INQUIRY, e.g. a quick
sequence of cable plugout and plugin, can result in failed INQUIRY.
This does not seem to be something that should or could be addressed by
serialization.

Another dual-LU device to which I currently have access to, an
OXUF924DSB FireWire 800 to dual SATA bridge with firmware from MacPower,
has been successfully tested with this too.

This change is beneficial to environments with two or more FireWire
storage devices, especially if they are located on the same bus.
Management tasks that should be performed as soon and as quickly as
possible, especially reconnect, are no longer held up by tasks on other
devices that may take a long time, especially login with INQUIRY and sd
or sr driver probe.

Signed-off-by: Stefan Richter

firewire: core: use non-reentrant workqueue with rescuer

2011-05-10T20:53:45+00:00

firewire-core manages the following types of work items:

fw_card.br_work:
  - resets the bus on a card and possibly sends a PHY packet before that
  - does not sleep for long or not at all
  - is scheduled via fw_schedule_bus_reset() by
      - firewire-ohci's pci_probe method
      - firewire-ohci's set_config_rom method, called by kernelspace
        protocol drivers and userspace drivers which add/remove
	Configuration ROM descriptors
      - userspace drivers which use the bus reset ioctl
      - itself if the last reset happened less than 2 seconds ago

fw_card.bm_work:
  - performs bus management duties
  - usually does not (but may in corner cases) sleep for long
  - is scheduled via fw_schedule_bm_work() by
      - firewire-ohci's self-ID-complete IRQ handler tasklet
      - firewire-core's fw_device.work instances whenever the root node
        device was (successfully or unsuccessfully) discovered,
	refreshed, or rediscovered
      - itself in case of resource allocation failures or in order to
        obey the 125ms bus manager arbitration interval

fw_device.work:
  - performs node probe, update, shutdown, revival, removal; including
    kernel driver probe, update, shutdown and bus reset notification to
    userspace drivers
  - usually sleeps moderately long, in corner cases very long
  - is scheduled by
      - firewire-ohci's self-ID-complete IRQ handler tasklet via the
        core's fw_node_event
      - firewire-ohci's pci_remove method via core's fw_destroy_nodes/
        fw_node_event
      - itself during retries, e.g. while a node is powering up

iso_resource.work:
  - accesses registers at the Isochronous Resource Manager node
  - usually does not (but may in corner cases) sleep for long
  - is scheduled via schedule_iso_resource() by
      - the owning userspace driver at addition and removal of the
        resource
      - firewire-core's fw_device.work instances after bus reset
      - itself in case of resource allocation if necessary to obey the
        1000ms reallocation period after bus reset

fw_card.br_work instances should not, and instances of the others must
not, be executed in parallel by multiple CPUs -- but were not protected
against that.  Hence allocate a non-reentrant workqueue for them.

fw_device.work may be used in the memory reclaim path in case of SBP-2
device updates.  Hence we need a workqueue with rescuer and cannot use
system_nrt_wq.

Signed-off-by: Stefan Richter 
Reviewed-by: Tejun Heo

firewire: octlet AT payloads can be stack-allocated

2011-05-10T20:53:44+00:00

We do not need slab allocations anymore in order to satisfy
streaming DMA mapping constraints, thanks to commit da28947e7e36
"firewire: ohci: avoid separate DMA mapping for small AT payloads".

(Besides, the slab-allocated buffers that firewire-core, firewire-sbp2,
and firedtv used to provide for 8-byte write and lock requests were
still not fully portable since they crossed cacheline boundaries or
shared a cacheline with unrelated CPU-accessed data.  snd-firewire-lib
got this aspect right by using an extra kmalloc/ kfree just for the
8-byte transaction buffer.)

This change replaces kmalloc'ed lock transaction scratch buffers in
firewire-core, firedtv, and snd-firewire-lib by local stack allocations.
Perhaps the most notable result of the change is simpler locking because
there is no need to serialize usages of preallocated per-device buffers
anymore.  Also, allocations and deallocations are simpler.

Signed-off-by: Stefan Richter 
Acked-by: Clemens Ladisch

firewire: use split transaction timeout only for split transactions

2011-01-04T07:48:34+00:00

Instead of starting the split transaction timeout timer when any request
is submitted, start it only when the destination's ACK_PENDING has been
received.  This prevents us from using a timeout that is too short, and,
if the controller's AT queue is emptying very slowly, from cancelling
a packet that has not yet been sent.

Signed-off-by: Clemens Ladisch 
Signed-off-by: Stefan Richter

firewire: make PHY packet header format consistent

2010-12-13T19:39:14+00:00

Change the header of PHY packets to be sent to include a pseudo
transaction code.  This makes the header consistent with that of
received PHY packets, and allows at_context_queue_packet() and
log_ar_at_event() to see the packet type directly instead of having
to deduce it from the header length or even from the header contents.

Signed-off-by: Clemens Ladisch 
Signed-off-by: Stefan Richter